1. Field of the Invention
This invention relates to novel elsamicin A derivatives which have better water solubility, improved antitumor activity, and/or reduced toxicity, to their production, to compositions containing the same as the active ingredient, and a method for therapy using said compositions.
2. Description of the Prior Art
Elsamicin A is an antitumor antibiotic produced by cultivating an elsamicin A-producing strain of actinomycete designated strain J907-21 (ATCC 39417), or a mutant thereof. Elsamicin A exhibits antibacterial activity against aerobic gram-positive bacteria and anaerobic bacteria. It also exerts activity against various murine tumor cells including leukemia P388, lymphoid leukemia L1210, and melanotic melanoma B16 in vitro and in vivo. Konishi, et al, Elsamicins, new antitumor antibiotics related to chartreusin. I. Production, isolation, characterization and antitumor activity, J. Antibiotics, 39: 784-791, (1986); U.S. Pat. No. 4,518,589 to Konishi, et al, issued May 21, 1985.
The structure of elsamicin A (Formula I, below) has been determined and shown to be closely related to chartreusin (Formula II, below). Sugawara, et al, Elsamicins A and B, new antitumor antibiotics related to chartreusin. II. Structures of elsamicins A and B. J. Org. Chem., 52: 996-1001, (1987). ##STR1##
Both elsamicin A and chartreusin have the same aglycone, chartarin, but the antibiotics differ in the disaccharide moiety. Leach, et al, Chartreusin, a new antibiotic produced by Streptomyces chartreusis, a new species, J. Am. Chem. Soc., 75: 4011-4012, (1953); Beisler, J. A., Chartreusin, a glycosidic antitumor antibiotic for Streptomyces, In progress in Medicinal Chemistry, Ed., G. P. Ellis and G. B. West 19: pp. 247-268, Elsevier Biomedical Press Amsterdam, (1982); Simonitsch, et al: Uber die Struktur des Chartreusins I, Helv. Chim. Acta, 47: 1459-1475, (1964); Eisenhuth, et al, Uber die Struktur des Chartreusins II, Helv. Chim. Acta, 47, 1475-1484, (1964). Interconversion of both compounds by chemical process has never been reported.
In the course of chemical modification of elsamicin A, we found that 2"-amino group of elsamicin A was selectively modified by acylation or alkylation to give new elsamicin A derivatives having better water solubility, improved antitumor activity and/or reduced toxicity.